Field of the Invention
The present invention relates to a flexible thermoelectric module apparatus, and more particularly, to a flexible thermoelectric module apparatus including a heat sink longitudinally extending and a thermoelectric module disposed in the heat sink, in which the heat sink has a pipe-shaped body constituting a main body and a hole longitudinally formed through the center portion of the body, the thermoelectric module has a plurality of thermoelectric plates, the thermoelectric plates are plates having predetermined length and width, are arranged longitudinally in parallel with the heat sink, with a first side in the width direction connected to the inner side of the body and a second side disposed inside the hole, are arranged in parallel with each other at circumferentially predetermined distances from each other in the hole, and have a predetermined angle to the radial direction of the heat sink such that they are inclined at a predetermined angle therebetween.
Description of the Related Art
An internal combustion engine generates power by burning specific fuel. In this process, a large amount of waste heat is produced, and particularly, a large amount of waste heat is included in an exhaust gas discharged through an exhaust pipe.
A thermoelectric element is a device that generates electricity, using a temperature difference, and when electricity is generated using waste heat, energy can be recycled and energy efficiency of an internal combustion engine can be improved.
However, it is an important problem for the thermoplastic element to increase energy generation efficiency by increasing the temperature difference between a hot side and a cold side of thermoelectric elements.
It is very important to study high-efficiency thermoelectric active materials in the thermoelectric field. A property of a thermoelectric material, so-called figure of merit is expressed by ZT.
  ZT  =                              S          2                ⁢        σ            k        ⁢    T  
In this equation, Z is figure of merit of a thermoelectric material, S is seebeck coefficient, σ is electric conductivity, k is thermal conductivity, and T is temperature. In order to achieve high figure of merit, high seebeck coefficient and electric conductivity and low thermal conductivity are required. Since the thermal conductivity follows Wiedemann-Franz law, so it is difficult to control independently from the electric conductivity, but it is possible to decrease the entire thermal conductivity by controlling the nano-structure of a material.
Since Bi2Te3 has been discovered as a low-temperature thermoelectric material, the maximum ZT remains now at about 1. When ZT is larger than 2, a thermoelectric system may concur with a common technology of, for example, temperature control. The use and application of thermoelectrics depend directly on the parameter, ZT, and when a thermoelectric element is formed in a module, the following efficiency equation is obtained.
  η  =                    Δ        ⁢                                  ⁢        T                    T        h              ·                                        1            +            ZT                          -        1                                          1            +            ZT                          ·                              T            c                                T            h                              
In this equation, ZT is a property of a thermoelectric material, ΔT is Th−Tc, Th is at the temperature of a hot side, at a portion being in contact with an exhaust pipe and Tc is the temperature of a cold side, at a portion attached to a heat sink.
As can seen from the equation, even if there is a difference of 1° C. or more between Th and Tc, a thermoelectric module generates electric energy, and the larger the difference between Th and Tc, the larger the efficiency. For example, for ZT=1, ΔT=50° C., Th=100° C., and Tc=50° C.,
  η  -            50      100        ·                                        1            +            1                          -        1                                          1            +            1                          +                  50          100                      -  0.10819  -      about    ⁢                  ⁢    10.82    ⁢    %  
Efficiency of about 10.82% is achieved, and when the number of flexible thermoelectric modules increases, more electric energy will be generated.
However, when the temperature of the hot side increases, the efficiency decreases in the equation, so it is required to increase the temperature difference between the cold side and the hot side as much as the increase in temperature of the hot side.